Semiconductor device and manufacturing process thereof

ABSTRACT

One of the aspects of the present invention is to provide a semiconductor device, which includes a circuit board, a first semiconductor chip mounted on the circuit board, a built-in semiconductor package on the first semiconductor chip, and a first molded resin encompassing the first semiconductor chip and the built-in semiconductor package. The built-in semiconductor package includes at least one second semiconductor chip mounted on a die pad, and the second semiconductor chip has a plurality of terminals. Also, the built-in semiconductor package includes a plurality of lead frames, and each of the lead frames is electrically connected with respective one of the terminals of the second semiconductor chip, and has a connection region on one side and a support region on the other opposing side. Further, the built-in semiconductor package a second molded resin encompassing the die pad, the second semiconductor chip, and the lead frames so that each of the connection regions is exposed and each of the support regions is covered. While the second molded resin has top and bottom surfaces, a plane flush with the connection region locates between the top and bottom surfaces of the second molded resin.

CROSS-REFERENCE TO RELATED APPLICATION

The present divisional application claims the benefit of priority under35 U.S.C. §120 to application Ser. No. 11/132,292, filed May 19, 2005,and under 35 U.S.C. § 119 from Japanese application No. 2004-149912,filed on May 20, 2004, the entire contents of both are herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

1) Technical field of the Invention

The present invention relates to a semiconductor device and amanufacturing process thereof, and in particular, relates to so-called amulti-chip-package semiconductor device integrating a plurality of chipswithin one package and the manufacturing process thereof.

2) Description of Related Arts

Recent innovation of many electrical apparatuses in downsizing andmulti-functioning also demands downsizing and multi-functioning ofsemiconductor devices incorporated in the electrical apparatus. Tosatisfy this demand, various semiconductor devices have been proposed,including a semiconductor device having a single semiconductor IC chipintegrating a memory circuitry and a logic circuitry. Alternatively, atechnique well known as a System in Package (SiP) has been developed, inwhich a memory IC chip and a logic IC chip are integrated within asingle package.

The semiconductor IC chip having a plurality of circuitries servingdifferent functions requires, when compared with a mono-functioning ICchip, a more prolonged design period and a more extended production linefor various steps of the manufacturing process, thereby causing theproduction yield to be reduced. Also, the multi-functioningsemiconductor IC chip has, in general, a chip surface that becomes widerthan the mono-functioning chip.

Meanwhile, the above-referenced conventional SiP technology proposes,for example, the semiconductor device including a plurality ofsemiconductor chips arranged in parallel on a printed circuit board.However, those semiconductor chips which are arranged in parallel on theboard and molded with resin also prevents the package size of thesemiconductor device, i.e., the mounting area of the semiconductordevice to the board from being reduced.

In addition, many other semiconductor devices are well known, which hasone semiconductor chip mounted on another semiconductor chip by means ofthe SiP technology. For example, the Japanese Patent Application No.11-288977 illustrates, in FIG. 1, a stacked chip 11 including asemiconductor chip 3 with a memory circuitry 8 stacked on asemiconductor chip 1 with a logic circuitry 3. Also, FIG. 3 shows thatthe stacked chip 11 is mounted on a board 12 and an insulating resin ismolded fully covering the stacked chip 11. Further, in FIG. 5, thestacked chip 11 is mounted on a plurality of inner leads 18 and also theinsulating resin is molded that wholly encompasses the stacked chip 11.

However, in case where one (upper) semiconductor chip is mounted onanother (lower) semiconductor chip, the chip size of the uppersemiconductor chip has to be smaller than the bonding pad region of thelower semiconductor chip, thus, the upper semiconductor chip has aconstraint in the chip size. Also, as the number of semiconductor chipsmolded in the semiconductor device increases, the semiconductor devicemay totally be condemned at a final inspection step even if only one ofthe semiconductor chips fails. This reduces the production yield of thesemiconductor device thereby to raise the manufacturing cost thereof.

SUMMARY OF THE INVENTION

To address the aforementioned drawbacks, one of the aspects of thepresent invention is to provide a semiconductor device including aplurality of semiconductor chips with different functions and reducingthe package size and thickness in a direction vertical to the mountingsurface, and a manufacturing process thereof.

In particular, one of the aspects of the present invention is to providea semiconductor device, which includes a board, a first semiconductorchip mounted on the board, a built-in semiconductor package on the firstsemiconductor chip, and a first molded resin encompassing the firstsemiconductor chip and the built-in semiconductor package. The built-insemiconductor package includes at least one second semiconductor chipmounted on a die pad, and the second semiconductor chip has a pluralityof terminals. Also, the built-in semiconductor package includes aplurality of lead frames, and each of the lead frames is electricallyconnected with respective one of the terminals of the secondsemiconductor chip, and has a connection region on one side and asupport region on the other opposing side. Further, the built-insemiconductor package a second molded resin encompassing the die pad,the second semiconductor chip, and the lead frames so that each of theconnection regions is exposed and each of the support regions iscovered. While the second molded resin has top and bottom surfaces, aplane flush with the connection region locates between the top andbottom surfaces of the second molded resin.

Further scope of applicability of the present invention will becomeapparent from the detailed description given herein. However it shouldbe understood that the detailed description and specific examples, whileindicating preferred embodiments of the invention, are given by way ofillustration only, since various changes and modifications within thesprit and scope of the invention will become apparent to those skilledin the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention more fully be understood from the detaileddescription given herein and accompanying drawings which are given byway of illustration only, and thus are not limitative of the presentinvention.

FIG. 1 is a cross sectional view of a semiconductor device according tothe first embodiment of the present invention.

FIGS. 2A and 2B are exploded cross sectional views of the semiconductordevice of FIG. 1.

FIG. 3 is a top plan view of the semiconductor device of FIGS. 2A and2E.

FIG. 4 is a cross sectional view of another semiconductor devicecontrastive to one of FIG. 1.

FIG. 5 is a flow chart illustrating a manufacturing process of thesemiconductor device of FIG. 1.

FIG. 6 is a cross sectional view of the built-in semiconductor packageof FIG. 1.

FIG. 7 is a cross sectional view of another built-in semiconductorpackage according to the second embodiment of the present invention.

FIG. 8 is a cross sectional view of another built-in semiconductorpackage according to the third embodiment of the present invention.

FIG. 9 is a cross sectional view of a board semiconductor packageaccording to the fourth embodiment of the present invention.

FIG. 10 is a top plan view of another semiconductor device according tothe fifth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the attached drawings, the details of embodiments accordingto the present invention will be described herein. In thosedescriptions, although the terminology indicating the directions (forexample, “upper” and “lower”) is conveniently used just for clarity, itshould not be interpreted that those terminology limit the scope of thepresent invention.

Embodiment 1

With reference to FIGS. 1 to 6, a semiconductor device according to thefirst embodiment of the present invention will be described herein. Asillustrated in FIGS. 1, 2A and 2B, the semiconductor device includes, ingeneral, a board type semiconductor package 10, a built-in typesemiconductor package 30 mounted thereon (which are referred herein tosimply as a “board semiconductor package” and a “built-in semiconductorpackage”), and a first molded resin 12 encompassing those semiconductorpackages 10, 30. For clarity, the hatching of the first molded resin 12is eliminated in FIG. 1, and the first molded resin 12 is not shown inFIG. 2.

As shown in FIGS. 1 and 2B, the board semiconductor package 10 includesa printed circuit board 14 and a first semiconductor chip 18 (e.g., alogic IC chip) mounted on an upper surface 16 of the printed circuitboard 14 via any conductive adhesive such as solder (not shown).

As illustrated in FIG. 3, the printed circuit board 14 has a rectangularplanar shape having two pairs of opposing members (four members) and aplurality of bonding pads 20 for the first semiconductor chip 18, whichare arranged on the upper surface 16 and along the four members. It alsoincludes a plurality of bonding pads 32 for the built-in semiconductorpackage 30, which are arranged along one pair of the opposing members.Further, the logic IC chip 18 includes a plurality of terminals (bondingpads) 22 that are electrically connected with bonding pads 20 of theprinted circuit board 14 via a plurality of conductive wires 24 such asgold wires. (For clarity, illustration of the conductive wires 24 ispartially eliminated in FIG. 3.)

Also, the printed circuit board 14 generally includes a plurality oflands (not shown) arranged on the lower surface 26 in a grid array and aplurality of conductive bumps such as solder bumps (see FIGS. 1 and 2B).However, if the thickness of the semiconductor device 1 is desired to beminimized, the solder bumps may be eliminated.

Meanwhile, the built-in semiconductor package 30 includes, as shown inFIGS. 1 and 2A, a die pad 34, at least one second semiconductor chip 36(e.g., a memory IC chip) mounted on the lower surface of the die pad 34via a conductive adhesive such as solder (not shown), and a plurality oflead frames 38. The memory IC chip 36 has a plurality of terminals (notshown), each of which is electrically connected with respective one ofthe lead frames 38 via the gold wire 40.

Each of the lead frames 38 has a connection region 42 on an upper sideand a support region 44 on the other opposing side (lower side), asillustrated in FIG. 2A. Also, the built-in semiconductor package 30includes a second molded resin 46 encompassing the whole of the die pad34, the memory IC chip 36, and the lead frames 38 except the connectionregions 42. (Again, for clarity of figures, the hatching of the secondmolded resin 46 is eliminated.) Thus, the second molded resin 46 isformed such that each of the connection regions is exposed and each ofthe support regions is covered and supported by the second molded resin46.

Further, after the built-in semiconductor package 30 is mounted on thefirst semiconductor chip 18 as shown in FIG. 3, each of the connectionregions 42 of the lead frames 38 are electrically connected withcorresponding one of the bonding pads 32 of the printed circuit board 14via conductive wires 48. (For clarity, illustration of the conductivewires 48 is partially eliminated in FIG. 3.)

By the way, when viewed in the cross sectional direction, as shown inFIG. 1, the gold wire 48 for connection between the connection regions42 of the lead frames 38 and the bonding pads 32 of the printed circuitboard 14 draws, in general, a curve with an upwardly convex peak. Thus,the gold wire 48 goes up by a rising distance d from the connectionregion 42 in the thickness (vertical) direction and approaches down tothe bonding pad 32. Therefore, suppose if the connection regions 42 ofthe lead frames 38 is located in a plane flush with a top surface(package surface) 50 of the built-in semiconductor package 30 asillustrated in FIG. 4, then the first molded resin 12 must have thethickness greater than the rising distance d to allow the gold wire tobe covered with the first molded resin 12. In other words, the thicknessbetween the connection region 42 and a top surface (package surface) 52of the first molded resin 12 should be set more than the rising distanced.

However, as clearly shown in FIG. 1, since the built-in semiconductorpackage 30 according to the present invention has the connection region42 located below the top surface 50 of the second molded resin 46 by thedistance D which can cancel or absorb the rising distance d of the goldwire 48. In other words, a plane flush with the connection region 42locates between the top surface 50 and the bottom surface 51 of thebuilt-in semiconductor package 30 (see FIG. 2A) for substantiallyreducing the thickness of the first molded resin 12 and as well as thethickness of the semiconductor device 1.

More preferably, the connection region 42 is designed such that thedistance D between the connection region 42 and the top surface 50 isgreater than the rising distance d of the gold wire 48. This preventsthe thickness of the semiconductor device 1 from increasing due to thegold wire 48 having the upwardly convex peak.

As described above, since a plurality of semiconductor chips 18, 36 withdifferent functions are integrated within one package, the functionalityof the semiconductor device 1 according to the present invention cansubstantially be enhanced.

In the above description, the electrical connection between the firstsemiconductor chip 18 and the printed circuit board 14 is described asbeing made by means of a plurality of conductive wires, i.e., in awire-bonding process, it may equally be made by a plurality ofconductive bumps, i.e., in a flip-chip bonding process. Thus, the firstsemiconductor chip 18 may be electrically connected with the printedcircuit board 14 via a plurality of conductive bumps (not shown).Therefore, any package size of the built-in semiconductor package 30 canbe stacked on the first semiconductor chip 18 because no gold wire 24 isbonded. This eliminates the constraint for the chip size of the upper(second) semiconductor chip 36, which is one of the drawbacks of thesemiconductor device of the conventional SiP technology, therebyfacilitating the design of the multi-chip-package semiconductor device.

Furthermore, according to the present embodiment, since a plurality ofsemiconductor chips 18 and 36 are stacked in the vertical direction, thepackage size of the semiconductor device 1 can be reduced in thetraverse direction. Also, since a plane flush with the connection region42 locates between the top and bottom surfaces 50, 51 of the built-insemiconductor package 30, the thickness in the vertical direction of thesemiconductor device 1 can be further reduced.

In addition, as will be described herein in more detail, since thesupport region 44 of the lead frame 38 opposing to the connection region42 is supported by the second molded resin 46, the wire bonding on theconnection region 42 can be facilitated.

Next, referring to FIGS. 5 and 6, a manufacturing process of thesemiconductor device 1 according to the present invention will bedescribed herein.

Firstly, the steps for manufacturing the built-in semiconductor package30 will be described. In the step ST10 of the flow chart indicated inFIG. 5, the second semiconductor chip (e.g., memory IC chip) 36 isbonded on the die pad as illustrated in FIG. 6. It should be noted thatthe built-in semiconductor package 30 of FIG. 6 is flipped over whencomparing with one of FIGS. 1 and 2A.

In the step ST12, a plurality of gold wires 40 are bonded both on theterminals of the memory IC chip 36 and on respective one of the leadframes 38 in the wire bonding process.

In the step ST14, a resin package is molded to encompass the die pad 34,the memory IC chip 36, and the lead frames 38, so that each of theconnection regions 42 is exposed and each of the support regions 44 iscovered.

In the step ST16, the electrical performance test of the built-insemiconductor package 30 so produced is made for securing rejection ofinferior products.

Secondary, the steps for manufacturing the board semiconductor package10 will be described. In the step ST20, the printed circuit board 14 isprepared, which includes a plurality of bonding pads 20, 32 on the uppersurface 16 for the first semiconductor chip 18 and the built-insemiconductor package 30, respectively, and also includes a plurality oflands on the lower surface 26 for connection to the external device (notshown). If necessary, a plurality of solder bumps 28 are provided on thelands.

In the step ST22, the first semiconductor chip (e.g., logic IC chip) 18is mounted on the upper surface 16 of the printed circuit board 14.

Next, in the steps ST24, the gold wires 24 are bonded both onto theterminals 22 of the logic IC chip 18 and the bonding pads 20 of theprinted circuit board 14. As described above, the electrical connectionbetween the logic IC chip 18 and the printed circuit board 14 may beachieved by means of the flip-chip bonding process.

Then, in the step ST26, the electrical performance test of the boardsemiconductor package 10 so assembled is conducted for rejecting anyinferior products.

In the step ST30, the built-in semiconductor package 30 accepted at theperformance test is flipped over (to direct the connection regions 42upwardly) as shown in FIG. 2A, and is mounted on the first semiconductorchip 18 as shown in FIG. 2B.

In the step ST32, each of the connection regions 42 of the lead frames38 is electrically connected with respective one of the bonding pads 32of the printed circuit board 14 via gold wires 48. According to thepresent embodiment, since the support regions 44 of the lead frames 38opposing to the connection regions 42 are securely supported by thesecond molded resin 46, the gold wires 48 are readily bonded onto theconnection regions 42. In other words, unless the support regions 44 aresupported, the lead frames 38 will not be able to endure the forceapplied during the wire-bonding and bend downwardly, thereby preventingthe gold wires 48 from being bonded in a reliable manner.

In the step ST34, the first molded resin 12 is formed encompassing thefirst semiconductor chip 18 and the built-in semiconductor package 30 tofinalize the semiconductor device 1.

Lastly, in the step ST36, the final electrical performance test is madefor the semiconductor device 1.

As above, according to the manufacturing process of the semiconductordevice 1 of the present invention, the board semiconductor package 10and the built-in semiconductor package 30 are individually inspected,and then the only accepted packages 10, 30 are assembled together.Therefore, the production yield of the semiconductor device 1 at thestep ST36 can remarkably be improved thereby to substantially reduce themanufacturing cost thereof.

Embodiment 2

Referring to FIG. 7, another semiconductor device according to thesecond embodiment of the present invention will be described herein. Thesemiconductor device 1 of the second embodiment is similar to that ofthe first embodiment except that at least one semiconductor chip ismounted on the upper and lower surfaces of the die pad of the built-insemiconductor package, respectively. The components shown in FIG. 7similar to those in FIG. 2A have the reference numerals similar thereto,and the duplicate description for the similar structure of the secondembodiment will be eliminated.

As illustrated in FIG. 7 corresponding to FIG. 2A of the firstembodiment, the built-in semiconductor package 30 of the secondembodiment includes at least two semiconductor chips (e.g., a flushmemory and a static random access memory) 60, 62, each of which ismounted on the upper and lower surfaces of the die pad 34, respectively.The flush memory 60 and the static random access memory 62 have aplurality of terminals (not shown), each of which are electricallyconnected with the lead frames 38 via the gold wires 64, 66,respectively.

As can be seen in those drawings, since the built-in semiconductorpackage 30 of the second embodiment includes more semiconductor chips60, 62 in number than that of the first embodiment, the functionality ofthe semiconductor device 1 can be further enhanced.

Also, in the built-in semiconductor package 30 of the second embodiment,as the first embodiment, the resin package (the second molded resin 46)is molded such that each of the connection regions 42 is exposed andeach of the support regions 44 is covered. Therefore, the gold wires 48can readily be bonded onto the connection regions 42 of the lead frames38 in a reliable manner.

Furthermore, since the connection regions 42 are located below the toppackage surface 50 of the built-in semiconductor package 30, the totalthickness of the semiconductor device 1 can be reduced.

Embodiment 3

Referring to FIG. 8, another semiconductor device according to the thirdembodiment of the present invention will be described herein. Thesemiconductor device 1 of the third embodiment is similar to that of thefirst embodiment except that another third semiconductor chip is mountedon the second semiconductor chip on the die pad. The components shown inFIG. 8 similar to those in FIG. 2A have the reference numerals similarthereto, and the duplicate description for the similar structure of thethird embodiment will be eliminated.

As above, in FIG. 8 corresponding to FIG. 2A of the first embodiment,the built-in semiconductor package 30 of the third embodiment includes asecond semiconductor chip (e.g., a flush memory) 70 on the lower surfaceof the die pad 34, on which a third semiconductor chip (e.g., the staticrandom access memory) 72 is further mounted. The static random accessmemory 72 has a surface area greater than that of the flush memory 70.The flush memory 70 and the static random access memory 72 each have aplurality of terminals (not shown), which are electrically connectedwith the lead frames 38 via the gold wires 64, 66, respectively.

The built-in semiconductor package 30 so structured of the thirdembodiment includes more semiconductor chips 70, 72 in number than thatof the first embodiment, the functionality of the semiconductor device 1can be further enhanced.

Also, the built-in semiconductor package 30 of the third embodiment ismolded with resin such that each of the connection regions 42 is exposedand each of the support regions 44 is covered. Therefore, the wirebonding process can readily and reliably be achieved for electricalconnection between the connection regions 42 of the lead frames 38 andthe bonding pads 32 of the printed circuit board 32.

In addition, as the connection regions 42 are located between the topand bottom surfaces 50, 51 of the built-in semiconductor package 30, thetotal thickness of the semiconductor device 1 can be reduced.

Embodiment 4

Referring to FIG. 9, another semiconductor device according to thefourth embodiment of the present invention will be described herein. Thesemiconductor device 1 of the fourth embodiment is similar to that ofthe first embodiment except that the board semiconductor package hasanother fourth semiconductor chip is mounted on the third semiconductorchip on the printed circuit board. The components shown in FIG. 9similar to those in FIG. 2B have the reference numerals similar thereto,and the duplicate description for the similar structure of the fourthembodiment will be eliminated.

As above, in FIG. 9 corresponding to FIG. 2B of the first embodiment,the board semiconductor package 10 of the fourth embodiment includes afourth semiconductor chip (e.g., a logic IC chip) 80 directly mounted onthe first semiconductor chip 18. The semiconductor chips 18, 80 eachhave a plurality of terminals, which are electrically connected withrespective one of the bonding pads 20 of the printed circuit board 14via gold wires 82, 84, respectively.

The semiconductor device 1 according to the fourth embodiment can beproduced by mounting any one of the built-in semiconductor package 30described above onto the fourth semiconductor chip 80, and by moldingthe whole of the board semiconductor package 10 and the built-insemiconductor package 30 with the first molded resin 12.

The board semiconductor package 10 so structured of the fourthembodiment includes various semiconductor chips 18, 80 than that of thefirst embodiment, the functionality of the semiconductor device 1 can befurther enhanced.

Embodiment 5

Referring to FIG. 10, another semiconductor device according to thefifth embodiment of the present invention will be described herein. Thesemiconductor device 1 of the fifth embodiment is similar to that of thefirst embodiment except that the built-in semiconductor package has aplurality of lead frames extending from each one of four members thereofand that the board semiconductor package has a plurality of bonding padsarranged along each of the members on the upper surface thereof.

As illustrated in FIG. 10 corresponding to FIG. 3 of the firstembodiment, the printed circuit board 14 of the fifth embodiment has arectangular planar configuration with four members and includes aplurality of bonding pads 20, 32 for the first semiconductor chip 18 andthe built-in semiconductor package 30, respectively. Those bonding pads20, 32 are arranged on the upper surface 16 and along each of themembers of the printed circuit board 14. Also, the built-insemiconductor package 30 of the fifth embodiment also has a rectangularplanar shape with four members and includes a plurality of lead frames38 extending from each of the members. Each of the lead frames 38 iselectrically connected with respective one of the bonding pads 32.

Thus, extension of the lead frames 38 from each one of four members ofthe built-in semiconductor package 30 allows more lead frames in numberto connect with the bonding pads 20, 32 of the printed circuit board 14.Therefore, according to semiconductor device 1 of the fifth embodiment,the number of the electrical connection paths can readily be increasedwithout expanding the area of the semiconductor device 1.

1. A method of manufacturing a semiconductor device comprising steps of:providing a semiconductor package having a memory IC chip integrating amemory circuitry, a molded resin encompassing the first semiconductorchip and a plurality of connection terminals electrically connectingwith the memory IC chip, exposed on a surface of the semiconductorpackage; providing a circuit board; providing a logic IC chipintegrating a logic circuitry; testing electrical performance of thesemiconductor package; after the testing step, mounting thesemiconductor package and the logic IC chip over the circuit board andelectrically connecting the memory IC chip and the logic IC chip withthe circuit board; and molding a resin encompassing the semiconductorpackage and the logic IC chip.
 2. The method of manufacturing asemiconductor device according to claim 1, wherein after the moldingstep, the method further comprises a step of testing electricalperformance of the semiconductor device.
 3. The method of manufacturinga semiconductor device according to claim 1, wherein in the mountingstep includes mounting the logic IC chip on the circuit board andmounting the semiconductor package on the logic IC chip.